A meridian is an imaginary line that runs from the North Pole to the South Pole, helping us understand the Earth's geography. These lines are used in mapping and navigation to indicate longitude, which measures how far east or west a location is from the Prime Meridian, located in Greenwich, England. Meridians are essential for GPS technology and global positioning systems, allowing us to pinpoint exact locations on the planet. Each meridian is spaced evenly, with 360 degrees of longitude in total. This system helps travelers and explorers find their way, making it easier to connect with different places around the world.